﻿<p>An <em>IfcWorkCalendar</em> defines working and non-working time periods for tasks and resources. It enables to define both specific time periods, such as from 7:00 till 12:00 on 25th August 2009, as well as repetitive time periods based on frequently used recurrence patterns, such as each Monday from 7:00 till 12:00 between 1st March 2009 and 31st December 2009.</p>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC4.
</blockquote>

<p>A work calendar is a subtype of <em>IfcControl</em> and thus inherits the feature for controlling other objects through <em>IfcRelAssignsToControl</em>, which is used to define a work calendar for tasks (<em>IfcTask</em>) and resources (<em>IfcResource</em>). It also inherits a name and description attribute, whereas a name shall be given and a description may be given as an indication of its content and usage.</p>

<p>The definition of time periods can be derived from a base calendar and/or modified/defined by a set of working times and non-working exception times. All time periods defined by <em>IfcWorkCalendar.ExceptionTimes</em> override the time periods inherited from the base calendar (base calendar is defined as the next applicable calendar for the task or resource). Thus, exception times replace the working times from the base calendar.</p>

<p>Figure 2 shows the definition of a work calendar, which is defined by a set of work times and exception times. The work times are defined as recurring patterns with optional boundaries (applying from and/or to a specific date). The shown example defines a simple work calendar with working times Monday to Thursday 8:00 to 12:00 and 13:00 to 17:00, Friday 8:00 to 14:00 and as exception every 1st Monday in a month the work starts one hour later - i.e. the working time on every 1st Monday in a month is overriden to be 9:00 to 12:00 and 13:00 to 17:00. Both the working time and the exception time is valid for the period of 01.09.2010 till 30.08.2011.</p>

<table summary="instantiation diagram">
<tr><td><img src="../../../figures/ifcworkcalendar_instantiation_diagram.png"
alt="task type instantiation diagram" border="0"></td></tr>
<tr><td><p class="figure">Figure 2 &mdash; Work calendar instantiation</p></td></tr>
</table>
